Arc lamp



Aug. 1o 1926. 1,595,776

C. A. GREEN ARC LAMP Q I uuml i Z j W//M/V/ /////y Aug. l0 1926.

c. A. GREEN ARC LAMP Original-Filed O01; l1' 1922 2-SheetS-She0t 2 MII Patented ,AAug. 1.926.` r

AUNITED sixATrssv PATENT oFFlcE.

CHARLES A. GREEN, or CHICAGO, ILLINOIS., AssIGNoIt 'ro o. F.1EAsE COMPANY, A

' Acoaromi'rIoN yor ILLINOIS.

ABC LAMP.

' Original application nled October 11, 1922, Serial No. 598,672. Divided. and this application mcd J'une 18, 1925. Serial No. 38,069.

' -This invention relates to' improvements in are lamps used in blueprint work, `photoengraving, and other arts.

The object of the invention is to provide i an improved are lamp so constructed as to permit the use of higher voltages with increase of current and correspondingly longer and heavier arcs, the light from which contains a larger percentage of near violet and ultra-violet rays than is the case 'with arc lamps heretofore used for photographic work of this character. A Another object is to provide an are lamp in which it is possible to use a smaller globe l5 arc lamps of the same electrical capacity, orI of the samelsize. r

Additional objects Will be apparent from the description hereinafter given of one 2O embodiment of the invention as used in connection with a continuous lblueprint machine, although the invention is not limited to this embodiment thereof, orto said class of serv- 1ce. i

This applicationis a division of my copending application, Serial No. 593,672, iled October 11, 1922. In the drawings:

Fig. 1 is an elevation, partly in section, ofa part of a blueprint machine.`

Fig. 2 is a top plan view of the row of arc lamps used therein, and

Fig. 3 is'anelevation of said arc lamps. 'The blueprint machine` comprises a suitable frame 1 having a table 2, overwhich the operator slides the blueprint paper on which the tracings are superimposed. The tracings and the blueprint paper travel rear-- wardly under a guide 3 an upwardly ,along an endless belt 4 which slides over a curved glass support 5, and'isV` su ported and moved by a series'of rollersx, g and 8, the roller 6 constituting the driving roller.

The printing isdone as the prints travel slowly past the .curved 'sheet-of glass, the tracings and .blueprints issuing at the top of the machine and being fed forwardly onto a sheet metal supporting plate 9, over which vthey slide into a sheet metal receptacle 10.x The arc lamps are supported on a transverse pi e or conduit 11, carried by the frame o .the machine, each lamp having asupportingY frame 12 of non-magnetic malferial, preferably, aluminum. The lower end of this frame surrounds the conduit with a higher' energy input than in otherk .as a support for the structure:

11, providing a hinged support which permitsv the lamp. to be swung forwardly for inspection or trimming. The aluminum frame carries a supporting plate 130i magnetic material, such as cast-iron, on which the various parts of the arc lamp are mounted.` The mechanism for feeding thecarbon downwardly is mounted on this su port and includes a solenoid 14 ,and sultable clutch mechanism of well known con- A 'glass globe 15 -`is mounted on anvextension 16 constituting `part of the arc lamp aluminum frame. A reiector 17 is arranged` infront of the globe to distribute the light evenly to the rear over the blueprint paper. In the arc lamps used heretofore, the arc which formed between the upper and lower electrodes or carbons had a tendency to blow to one side, as an iron frame was employed It was, therefore, necessary to mount, the solenoid or magnet in each lamp fairly high afbove` the oints of the carbons, resulting In a long amp. In the present constructionthe frame is made of aluminum, which has a number 'of very desirable properties, includ- .ing lits non-magnetic property, and said frame is mounted below ythe solenoid, the

ylatter being mounted not far above the arc,

and the lamp being correspondingly short- In this construction, and with the arrangement of 'the arc lamps in a row, as shown in Figs. 2 and 3, the bowing of the are tok onevside has been greatly minimized.

Referring to Fig. 3, the arc which forms between the arbons-18 and 19 in each case has a tendency to blow to the right, vthis tendency being oiIset, however, -by the magnetic eld established by the solenoid of the adjacent lamp. Thel right hand lamp having no lamp to the right of it to corn-v y pensate in ltheqnannerv described, I provide a strip of magnetic material 20, preferably a piece o mild steel, which is secured to `,the right handlamp of the group, as shown in Figs 2 and 3.

Said strip brin s' the magnetic/field in such proximity to e arc asto counteract its tendency to blow to the right. As a result of this arrangement the arc is comparatively steady and centrally located with reference to the carbons.

In the/prior constructions,previously relferred to, thearo 1n blowing -out to `one tremities and the arc travels'slowly around said lower ends, consuming them evenly and furnishing a light which is free from shadows. As shown in Figs. 2 and 8, the supply wires 21 enter the conduit v11 with branch connections issuing from the.outlet boxes 22.' Figs. 2 and 3 also show a slightly 'diagonal arrangement of each lamp with reference to the axis of the supporting conduit. This arrangement results in some improvement in the magnetic field.4

. In the absence of the improvements described, bowing of the arcs occurs and disturbs the uniformity of the lighting eilect.

At the upper end of each globe, and within the same, is a casing 23 having suitable holes 24 in it to permit the escape of heated gases. By virtue of the smaller construction ot the frame and associated parts, previously referred to, I am enabled to use a smaller globe, which, in turn, results in drawing in the outside air more advantageously, the air being drawn in at the top of the globe and expelled intermittently through the same openings, as the succes-K sive installments of air heat up and expel themselves. Under these conditions less oxygen is drawn in at a time, and there is less irregularitfy in the heating. This permits the'use o said smaller globes without .danger of cracking them.

The construction described also permits the use-ot higher voltages with increase of current and correspondingly longer and heavier arcs. The longer arcs emit a greater proportion of rays effective for blueprinting -and photography generally than the shorter arcs, and increase the printing speed. With my improved construction I am enabled to increase the current usedtwentyfive percent with an increase in printing speed olfabout one hundred percent, withL improved results romthe standpoint of uniformity in the prints.

The improvements described herein are applicable both to alternating current and direct current lamps, although the improvement overthe prior practice is more pronounced in the case of lamps used on alter- Dating current circuits'- Heretofore it has been necessary to design arc lamps especially for alternating current or direct current use as applied to photographic work, whereas with my improved construction the same lamp may be used in either work, making it a universalarc lamp.

What I claim is;

1. An arc lamp comprising' a magnetic supporting plate, a solenoid mounted above the same, an aluminum frame depending from said plate, upper and lower electrodes supported from said plate and said aliiminum frame, respectively, and a globe enclosing said electrodes whereby the structure below said plate may be short without causing irregular consumption of said electrodes by the arc.4

2." An arc lamp comprising a supporting member` a solenoid, mounted above the same, a non-magnetic frame depending from said member, upper and lower electrodes on said member and said non-magnetic frame respectively, and a globe enclosing said electrodes whereby the structure below said member may be short without causing irregular consumption of said electrodes by the arc;

3. An electric arc lamp comprising a nonmagnetic frame, actuating mechanism 'for the carbons -moiinted above said frame, whereby the are maintains an average'central position with reference to the axis of said carbons, .a small globe supported by -said frame and surrounding the electrodes enabling a high voltage to be employed with large.- current consumption, resulting 1n a long arc within said globe and the development of light wave lengths suitable for photographic work.

4. An arc lamp comprising a supporting member, a solenoid arranged on one side of said member, a non-magnetic frame supported by said member, upper and lower electrodes, 'and a globe enclosing the same.

In testimony whereof, I have subscribed my name.v

` CHARLES A. GREEN. 

